Carburetor of the vacuum controlled type



2, 1955 H. w. M CLAIN CARBURETOR OF THE VACUUM CONTROLLED TYPE 2Sheets-Sheet 2 Filed Jan. 16, 1953 Jim-4.

United States Patent 2,714,502 CARBURETOR 0F 'IHEYIaAECUUM CONTROLLEDHarry W. McClain, Long Beach, Calif.

Application January 16, 1953, Serial No. 331,668 4 Claims. (Cl. 261-44)This invention relates to a carburetor of the vacuum controlled type inwhich a piston within the cylinder portion of the carburetor is causedto move due to a vacuum above the piston, and the movement of thispiston in turn controls a fuel needle valve to admit fuel into the airstream flowing into the engine.

An object of my invention is to provide a novel carburetor of thecharacter stated which is simple in construclevel.

Another feature of my invention is to provide a simple and effectivemeans to prevent excessive and rapid movement of the actuating piston inthe cylinder portion of the carburetor, this being accomplished by anoutside air bleed.

Other objects, advantages and features of invention may appear from theaccompanying drawing, the subjoined detailed description and theappended claims.

In the drawing:

Figure 1 is a longitudinal sectional view of the pre ferred form of mycarburetor.

Figure 2 is a sectional view taken on line 2--2 of Figure 1.

Figure 3 is a longitudinal sectional view of a modified form of mycarburetor.

Figure 4 is a sectional view Figure 3.

Figure 5 is a fragmentary side elevation of the piston mounted within mycarburetor.

Referring more particularly to the drawing, and especially to thepreferred form of my invention shown in Figures 1 and 2, in thisembodiment an intake pipe 1 is provided with the usual mounting flange 2so that the carburetor may be attached to the engine intake manifold 3.The pipe 1 opens into, also depends from, and is preferably an integralpart of a cylinder 4 which is considerably larger in diameter than thepipe 1. A throttle valve 5 of usual and well known design is mounted inthe pipe 1 and the position of this throttle valve determines the amountof air and entrained fuel which flows into the engine.

An air intake pipe 6 extends into the side of the cylinder 4 and thispipe admits air under atmospheric pressure into the carburetor. Thereciprocation of the pistons in the engine creates a vacuum and thisvacuum is highest when the throttle valve is closed. As the valve 5swings open the vacuum below the valve 5 is transferred to the space 7above the throttle valve. As vacuum is created in space 7 this vacuum isfilled by the air flowing in through the pipe 6. To satisfy and fill thevacuum in the taken on line 44 of 2,714,502 Patented Aug. 2, 1955 space7, I provide a cup or valve 8 which is caused to rise or fall, and thusvary the amount of air admitted to the space 7 through the intake pipe6. As the engine requires more air, the valve or cap 8 is caused to moveupwardly permitting more air to flow into the pipe 1 through the intakepipe 6 by the following construction:

A transverse wall 9 is provided in the cylinder 4 above the air intakepipe 6. A tube 10 rises from the cup or valve 8 and this tube alsoextends through the top of the cylinder 4. It will thus be evident thatthe tube 10 has two supports or hearing guides, one in the transversewall 9 and the other in the top wall of the cylinder 4. These twobearings preferably consist of metal rings 11 and 12 which accuratelyguide the tube and effectively support and guide the piston 13 which isfixedly attached to the tube 10 above the transverse wall 9. This piston13 is thus accurately guided and prevented from dragging against thewall of the cylinder 4. There is thus provided a chamber 14 above thepiston 13 and a second chamber 15 below the piston 13.

A fuel chamber 16 is mounted der 4 and the usual float 17 is mountedwithin the float chamber for the purpose of maintaining a constant fuellevel therein. A fuel intake pipe 18 extends from the fuel chamber 16into the pipe 1, and then extends upwardly at an elbow to a metering jet19. A tapered needle valve 20 extends into the metering jet 19 andthisneedle is attached to a rod 21 which is threaded into the upper end ofthe tube It). This threaded coupling permits the needle 20 to be raisedor lowered relative to the metering jet 19 to adjust proper fuelflow atdifferent speeds. A port 22 is provided through the wall of the tube 10above the piston 13, thus enabling the vacuum present in the chamber 7to be transferred to the chamber 14. These two chambers thus have thesame amount of vacuum at all times.

To prevent the piston 13 from violently moving upwardly or downwardly, Iprovide an air bleed 23 which can be manually adjusted by the screw 24,thus bleeding atmospheric air into the chamber 15 which acts as a checkto prevent the piston 13 from rapid movement. Any movement of thethrottle 5 towards an opening position will tend to increase the vacuumin the chamber 7. This increased vacuum is then transferred to thechamber 14. The piston 13 will thereupon move upwardly which carries theneedle 26 upwardly, opening the fuel metering jet 19 to admit fuel intothe incoming air which is moving through the intake pipe 6, thencearound the bottom of the cup valve 8, and thence downwardly through thepipe 1 and into the engine.

As long as air is coming into the chamber 7 it will satisfy the vacuumtherein and, consequently, the position of the piston 13 remainsconstant. This condition continues until the throttle valve 5 is eitheropened a greater amount or closed. If it is opened a greater amount thepiston 13 moves upwardly, thus moving the cup valve 8 upwardly andadmitting more air. valve 5 closes, the vacuum in the chamber 7decreases and the piston 13 drops to the position shown in Figure l.

A choke construction consists of a tube 25 which extends downwardly inthe fuel chamber 16 and is attached at its lower end to the fuel intakepipe 18 A needle valve 26 within the tube 25 rests on a seat at itslower end to normally close the opening into the tube 25. When theneedle valve 26 is raised manually by means of the bell crank 27 fuelwill be admitted to the tube 25 and this fuel rises in the tube andpasses through the duct 28 into the intake pipe 1 at approximately thesame level as the metering jet 19.

An altitude compensator consists of a pipe 29 which extends from the topof the fuel chamber 16 and thence into the chamber 14 through the sidewall of the cylinder on the side of the cylin- If the throttle 4. Airflows through the pipe 29 constantly while the carburetor is inoperation due to the fact that the chamber 14 is under a partial vacuum,as previously described. An air bleed is provided in the top of the fuelchamber 16 and the size of the port in this air bleed is such that atsea level enough air enters the bleed 30 to maintain atmosphericpressure on top of the fuel in the fuel chamber 16. At higher altitudes,due to less air pressure, the space above the fuel will be more rapidlyevacuated by the engine. Consequently, there will be less pressure onthe fuel and, as a result, less fuel will be moved to the fuel jet 19,thus providing a leaner mixture at higher altitudes.

In the modification, shown in Figures 3, 4 and 5, the intake pipeextends into the side of the cylinder 36, substantially as shown. An airintake pipe 37 extends into the side of the cylinder 36 opposite thepipe 35. A piston 38 is reciprocally mounted in the cylinder 36 and askirt 39 extends downwardly from the piston 38 and this skirt has anopening 40 in the side thereof, which opening faces towards the airintake pipe 37. A conduit 41 extends from the top of the intake pipe 35and thence into the upper part of the cylinder 36 so as to evacuate theupper chamber 42 within the cylinder and above the piston 38.

A tube 43 extends vertically through the piston 38 and through the topwall of the cylinder 36. The lower end of this tube extends into a dashpot 44 which is mounted below the cylinder 36. The tube 43 closely fitsthe dash pot and oil is provided in this pot as is usual and the oilbleeds through a port 45, thus restricting the movement of the piston38, particularly in an upward direction. A check valve 46 is alsoprovided in the bottom of the tube 43 and this check valve opens whenthe piston 38 drops. A needle valve 47 controls the opening of the portand this needle valve extends upwardly through the top of the tube 43. Afuel chamber 48 is positioned at one side of the cylinder 36 and a fuelsupply pipe 49 extends into the air intake pipe 35 and at the lower edgeof this pipe so that as the air enters from the intake pipe 37 the airwill pass across the pipe 49 and carry fuel into the engine.

A needle valve 50 is secured at its upper end to an arm 51 which extendshorizontally from the tube 43 and, consequently, the needle valve 50 israised and lowered as the piston 38 moves. The same altitude control isprovided, as previously described, consisting of the pipe 52 which isthe same as the pipe 29 previously described, and also the air bleed 53,which is the same as the air bleed 30 previously described. Theoperation of this carburetor is the same as previously described in thatthe piston 38 rises and falls with the amount of vacuum created in thechamber 54 above the throttle valve 55.

Having described my invention, I claim:

1. A carburetor comprising a cylinder, a pipe depending from thecylinder, a throttle valve in the pipe, an air intake pipe extendinginto the cylinder, said cylinder having a chamber therein into whichsaid pipe opens and said air intake pipe extends, a transverse Wall inthe cylinder defining the top of said chamber, a piston in saidcylinder, means on the piston movable with relation to said pipe tocontrol the flow of air into said pipe, a fuel chamber, a fuel pipeextending from the fuel chamber into said first named pipe, and a needlevalve projecting from the piston and extending into the fuel pipe tocontrol fuel flow from the fuel pipe, said cylinder having a chambertherein above the piston, and conduit means open to said first namedpipe and opening into the last named chamber to evacuate the last namedchamber and cause the piston to rise in the last named chamber, analtitude compensator comprising a pipe extending from the top of saidfuel chamber and into the last named chamber, said fuel chamber havingan air bleed port therein extending into the top thereof.

2. A carburetor comprising a cylinder, a pipe extending from thecylinder, a throttle valve in the pipe, an air intake pipe extendinginto the cylinder, said cylinder having a chamber therein into whichsaid pipe opens and said air intake pipe extends, a transverse wall inthe cylinder defining the top of said chamber, a piston in saidcylinder, a tube extending through the piston, means slidably mountingthe tube in the cylinder, a cup on the lower end of the tube of greaterdiameter than the tube and movable with relation to said first namedpipe to control the flow of air into said first named pipe, 21 fuelchamber, a fuel pipe extending from the fuel chamber into the firstnamed pipe, and a needle valve arranged Within the tube and dependingtherefrom, said needle valve extending into the fuel pipe to control thefuel flow from the fuel pipe, said cylinder having a chamber thereinabove the piston, said tube having a port therein opening into thechamber to evacuate the last named chamber and cause the piston to risein the last named chamber.

3. A carburetor comprising a cylinder, a pipe extending from thecylinder, a throttle valve in the pipe, an air intake pipe extendinginto the cylinder, said cylinder having a chamber therein into whichsaid pipe opens and said air intake pipe extends, a transverse wall inthe cylinder defining the top of said chamber, a piston in saidcylinder, a tube extending through the piston, means slidably mountingthe tube in the cylinder, a cup on the lower end of the tube of greaterdiameter than the tube and movable with relation to said first namedpipe to control the flow of air into said first named pipe, a fuelchamber, a fuel pipe extending from the fuel chamber into the firstnamed pipe, and a needle valve arranged Within the tube and dependingtherefrom, said needle valve extending into the fuel pipe to control thefuel flow from the fuel pipe, said cylinder having a chamber thereinabove the piston, said tube having a port therein opening into thechamber to evacuate the last named chamber and cause the piston to risein the last named chamber, an altitude compensator comprising a pipeextending from the top of said fuel chamber and into the last namedchamber, said fuel chamber having an air bleed port therein extendinginto the top thereof.

4. A carburetor comprising a cylinder, a pipe extending from thecylinder, a throttle valve in the pipe, an air intake pipe extendinginto the cylinder, said cylinder having a chamber therein into whichsaid pipe opens and said air intake pipe extends, a transverse wall inthe cylinder defining the top of said chamber, a piston in saidcylinder, a tube extending through the piston, means slidably mountingthe tube in the cylinder, a cup on the lower end of the tube of greaterdiameter than the tube and movable with relation to said first namedpipe to control the flow of air into said first named pipe, a fuelchamber, a fuel pipe extending from the fuel chamber into the firstnamed pipe, and a needle valve arranged within the tube and dependingtherefrom, said needle valve extending into the fuel pipe to control thefuel flow from the fuel pipe, said cylinder having a chamber there inabove the piston, said tube having a port therein opening into thechamber to evacuate the last named chamber and cause the piston to risein the last named chamber, said cylinder having a third chamber thereinbelow the piston and an air bleed extending into the third chamber, analtitude compensator comprising a pipe extending from the top of saidfuel chamber and into the last named chamber, said fuel chamber havingan air bleed port therein extending into the top thereof.

References Cited in the file of this patent UNITED STATES PATENTS1,813,866 Royce July 7, 1931 2,167,892 Kent et al. Aug. 1, 19392,363,223 Bonnier Nov. 21, 1944 2,646,264 Morris July 21, 1953

